Abstract: A railroad hopper car particularly adapted for shipment of dry, granular-like commodities may have its inner space divided into compartments which in turn are formed with chambers. Each chamber bottom includes a discharge system comprising a pair of aligned fluidizing conveyors which converge downward. Lower ends of the conveyors are spaced apart to define a chute outlet which includes a passageway through a chute portion of a slide gate discharge assembly. The passageway may be closed or opened by selective movement of a door plate connecting with a drive mechanism in a drive portion of the assembly. Commodity in the railroad car is maintained contamination free in part by isolating the chute and drive portion with seals that engage the door plate and a sanitary plate which pivots to close the passageway lower end. During commodity unloading the sanitary plate and door plate are located to clear the passageway through the chute outlet.